Although copper-base alloys generally possess higher strength and corrosion resistance than aluminum and zinc-base alloys, they are not pressure die cast to the same degree because their higher melting points (generally over 1600.degree. F.) cause shorter steel die life or require the use of more expensive die materials. It is generally felt that lower melting point copper-base alloys should improve die life and could therefore use to advantage the high volume, relatively low cost pressure die casting process. Such alloys could also be cast in sand, permanent and investment molds.
As used in the specification and claims, all composition percentages are by weight.
Alloys are known in the prior art which have melting points lower than standard copper-zinc die casting alloys. Certain alloys containing 2-6.8% phosphorus, 20-34% zinc, 0-1% lead, 0-8% nickel, balance copper, exhibit liquidus temperatures as low as 1252.degree. F., but have low tensile ductility when chill cast. Alloys containing as much as 25% antimony and 10% magnesium melt as low as 720.degree. C. (1328.degree. F.) but these, too, are brittle (less than 1% tensile elongation). Alloys containing 1-1.5% aluminum, 17-22% manganese, 17-22% zinc, and 58-60.5% copper have liquidus temperatures below 1850.degree. F., and generally in the range of 1550.degree. - 1600.degree. F. Thus, while copper-base alloys have been proposed which have low liquidus points, they find little commercial use because of poor mechanical properties. Conversely, those alloys which exhibit good mechanical properties have high liquidus points and wide freezing ranges, and are difficult to cast, particularly by die casting techniques.